Hope someone can help

I've recently purchased a 2001 1.6 Marea weekend. The engine light on the dash is on which I've checked with my elm327 lead and laptop and found codes P0141 & P0135 which I gather are both o2 sensor heater circuit problems. Car starts and runs fine.

I've put a multimeter across both white leads on each sensor and there is no continuity between the two. Have I missed something before I go and replace both sensors?

Thanks in advance for any advice.

Measured my old bosch and got about 9ohms on the white wires.
I guess you are correct. Nice for them to break at same time...

Changed the one under the car. It had obviously been taken out before or as the wires were twisted around each other and one heater wire was broken.

Not changed one on top of the manifold yet as tried to get out with a 22mm socket and a handle from a wheel wrench but didn't budge. Will try a bit of heat next when it eventually stops raining (if it does).